A drive unit with an electric motor for operating a plurality of adjusting devices for a vehicle seat is known from Japanese Patent Application 63-162 348 (A), wherein the electric motor is rotatably disposed in a cylinder-shaped housing and can be rotated parallel to its own longitudinal axis. The motor shaft and the input shafts of the adjusting devices are respectively provided with electromagnetic couplings. It is possible in this way to connect the motor shaft of the electric motor selectively with one of the input shafts of the adjusting devices.
The spatial displacement of the entire electric motor, however, requires much space and the availability of strong displacement forces, and an elaborate motor seating is also required to assure precise switching processes. Thus, the electric motor of the known device in seated in a cylinder-shaped housing which completely encloses the electric motor. However, this negatively affects the cooling of the motor and in this way reduces the available output of the motor.
A vehicle seat which can be adjusted by means of an electric motor is also known from German Patent Publication DE 34 03 246 A1, in which a single electric motor is assigned to a plurality of adjusting devices and the drive shaft of the electric motor can be selectively connected with one of the input shafts of the adjusting devices. The electric motor in this case can be mounted stationary on the seat frame of the vehicle seat and can be brought selectively into engagement with corresponding, axially displaceable coupling pieces for the individual adjusting device.
But since the individual adjusting devices are disposed at very different places on the vehicle seat, a shaft connection from the respectively associated coupling piece to the input shaft of the respective adjusting device is always required. The movable seating of the coupling pieces, however, is considerably elaborate.
For this reason, in another embodiment the electric motor is seated on the seat frame, so its location can be changed and it can be selectively displaced or pivoted into positions in which its drive shaft comes into engagement with a respectively stationary seated coupling piece which is respectively connected in a manner fixed against relative rotation via a shaft connection with the input shaft of an associated adjusting device. However, the variable seating of the complete electric motor on the seat frame requires a great structural outlay, as already explained above.